Cognitive Neuroscience of Eating Disorders

Optimizing treatment environments for trait sensitivity in eating disorders

Research has identified trait sensitivity as a potential risk factor and treatment target of eating disorders. Conceptualizations of trait sensitivity have depicted individuals with high and low trait sensitivity metaphorically as orchids and dandelions, highlighting their responsiveness to environmental conditions and associated outcomes. While orchids require careful tending to survive, with such care, they emerge extraordinary. In contrast, dandelions can survive a broad range of environmental conditions. Within a scientific framework, trait sensitivity can be conceptualized as neurobiologically-based, with heightened sensory, interoceptive, interpersonal, and emotional processing. While trait sensitivity may increase susceptibility to eating disorders, when therapists view these traits through the lens of environmental responsiveness, they can facilitate their client's inherent resilience and potential. Incorporating a model of trait sensitivity into eating disorders treatment using psychoeducation, modifying environmental stimuli, and selecting optimal interventions has the potential to increase treatment engagement, deepen therapeutic collaboration, and improve outcomes.

Dynamic Changes in Local Brain Connectivity and Activity: A Longitudinal Study in Adolescent Anorexia Nervosa

BACKGROUND

Resting-state functional connectivity analysis has been used to study disruptions in neural circuitries underlying eating disorder symptoms. Research has shown resting-state functional connectivity to be altered during the acute phase of anorexia nervosa (AN), but little is known about the biological mechanisms underlying neural changes associated with weight restoration. The goal of the current study was to investigate longitudinal changes in regional homogeneity (ReHo) among neighboring voxels, degree centrality (DC) (a voxelwise whole brain correlation coefficient), voxel-mirrored homotopic connectivity (VMHC) (measuring the synchronization between hemispheres), and the fractional amplitude of low-frequency fluctuations associated with weight gain during AN treatment.

METHODS

Resting-state functional connectivity data were acquired and analyzed from a sample of 174 female volunteers: 87 underweight patients with AN that were scanned before treatment and again after at least 12% body mass index increase, as well as 87 age-matched healthy control participants.

RESULTS

Longitudinal changes in ReHo, DC, VMHC, and the fractional amplitude of low-frequency fluctuations were observed in most regions identified to differ between patients with AN before treatment and healthy control participants. However, the degree of normalization varied for each parameter, ranging from 9% of all clusters in DC to 66% in VMHC. Longitudinal changes in ReHo and VMHC showed a linear association weight gain.

CONCLUSIONS

Resting-state functional magnetic resonance imaging measures, including ReHo, DC, VMHC, and the fractional amplitude of low-frequency fluctuations, show varying degrees of recovery after short-term weight restoration. Although only some of these changes were related to weight gain, our results provide an overall positive message, suggesting that weight restoration is associated with changes in functional brain measures that point toward normalization.

Associations between disordered eating, internalizing symptoms, and behavioral and neural correlates of response inhibition in preadolescence

Response inhibition difficulties are reported in individuals with eating disorders (EDs), anxiety, and depression. Although ED symptoms and internalizing symptoms co-occur in preadolescence, there is limited research examining associations between these symptoms and response inhibition in this age group. This study is the first to investigate the associations between behavioral and neural markers of response inhibition, disordered eating (DE), and internalizing symptoms in a community sample of preadolescents. Forty-eight children (M age = 10.95 years, 56.3% male) completed a Go/NoGo task, whereas electroencephalography was recorded. Self-report measures of DE and internalizing symptoms were collected. Higher levels of anxiety and depression were associated with neural markers of suboptimal response inhibition (attenuated P3NoGo amplitudes) in preadolescence. In contrast, higher levels of depression were associated with greater response inhibition at a behavioral level. These findings suggest internalizing symptoms in preadolescence are associated with P3-indexed difficulties in evaluation and monitoring, but these are not sufficient to disrupt behavioral performance on a response inhibition task. This pattern may reflect engagement of compensatory processes to support task performance. DE was not significantly associated with response inhibition, suggesting that difficulties in response inhibition may only be reliably observed in more chronic and severe DE and ED presentations.

Waiting for it: Anorexia Risk, Future Orientation, and Intertemporal Discounting

Anorexia Nervosa is a severe eating disorder characterized by food restriction in service of a future goal: thinness and weight loss. Prior work suggests abnormal intertemporal decision-making in anorexia, with more farsighted decisions observed in patients with acute anorexia. Prospective future thinking in daily life, or temporal orientation, promotes more farsighted delay discounting. However, whether temporal orientation is altered in anorexia, and underlies reduced delay discounting in this population, remains unclear. Further, because changes in delay discounting could reflect cognitive effects of an acute clinical state, it is important to determine whether reduced delay discounting is observed in subclinical, at-risk samples. We measured delay discounting behavior and temporal orientation in a large sample of never-diagnosed individuals at risk of anorexia nervosa. We found that farsighted delay discounting was associated with elevated risk for anorexia nervosa. Anorexia nervosa risk was also associated with increased future-oriented cognition. Future-oriented cognition mediated the difference in delay-discounting behavior between high and low-risk groups. These results were unrelated to subjective time perception and were independent of mood and anxiety symptomatology. These findings establish future-oriented cognition as a cognitive mechanism underlying altered intertemporal decision-making in individuals at risk of developing anorexia nervosa.

Neuronal activity and reward processing in relation to binge eating

PURPOSE OF REVIEW

Studies increasingly show the importance of reward processing in binge eating and provide evidence of associated changes in the neurobiological reward system. This review gives an up-to-date overview of the neurobiological substrates of reward processing subconstructs in binge eating. Neural findings are linked to different behavioral theories and the clinical relevance is discussed.

RECENT FINDINGS

Increased neural responses in the orbitofrontal cortex, anterior cingulate cortex as well as striatum during anticipation and receipt of food rewards are found in association to binge eating. Increased model-free learning is also found and associated with altered brain reward reactivity. Data in rest report reduced striatal dopamine release and lower frontostriatal connectivity. Mechanisms of onset of binge eating are less clear, but specific personality traits, related to frontostriatal dysconnectivity, probably increase the risk of binge eating onset.

SUMMARY

Both structural and task-based imaging studies show differences in the neurobiological reward system in binge eating. These changes are linked to specific reward processing, such as altered reward responsiveness to food cues, reinforcement learning, and habitual behavior. Findings are lined with different behavioral theories of binge eating, and a staging model is described, from onset to full illness development. Understanding the specific underlying aberrant reward mechanism in binge eating, associated with different stages of the illness, enables caregivers to focus their treatment more precisely.

Eating Disorders in U.S. Active Duty Military Members and Veterans: A Systematic Review

INTRODUCTION

Feeding and eating disorders can be difficult to treat and frequently co-occur with other mental health conditions. The last systematic review of eating disorders in a military and veteran population was published in 2015. An updated review is warranted to re-examine the current literature on eating disorders in the active duty and veteran populations.

MATERIALS AND METHODS

A systematic review that described the prevalence, co-occurrence of other disorders and/or events, and health care utilization of U.S. active duty members and veterans was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Databases and Medical Subject Headings (MeSH) terms used are listed in Appendix A. Each category of the literature was extracted and graded using the Oxford Centre for Evidence-Based Medicine Levels of Evidence.

RESULTS

Twenty-one studies revealed prevalence estimates with varying rates based on demographic information. Trauma exposure is consistently associated with eating disorder development. Individuals diagnosed with eating disorders had greater health care utilization.

CONCLUSIONS

Research on eating disorders in the military and veteran populations has expanded in recent years. Limitations of the evidence included in this review stem from the use of self-reported questionnaires, changes to medical record systems, and limited generalizability to the overall population of patients with eating disorders. Further research should investigate the impact of demographic factors and trauma exposure on the development of an eating disorder within the military and veteran populations.

Central Autonomic Network Alterations in Anorexia Nervosa Following Peripheral Adrenergic Stimulation

BACKGROUND

Anorexia nervosa (AN) is characterized by low body weight, disturbed eating, body image disturbance, anxiety, and interoceptive dysfunction. However, the neural processes underlying these dysfunctions in AN are unclear. This investigation combined an interoceptive pharmacological probe, the peripheral β-adrenergic agonist isoproterenol, with resting-state functional magnetic resonance imaging to examine whether individuals with AN relative to healthy comparison participants show dysregulated neural coupling in central autonomic network brain regions.

METHODS

Resting-state functional magnetic resonance imaging was performed in 23 weight-restored female participants with AN and 23 age- and body mass index-matched healthy comparison participants before and after receiving isoproterenol infusions. Whole-brain functional connectivity (FC) changes were examined using central autonomic network seeds in the amygdala, anterior insular cortex, posterior cingulate cortex, and ventromedial prefrontal cortex after performing physiological noise correction procedures.

RESULTS

Relative to healthy comparison participants, adrenergic stimulation caused widespread FC reductions in the AN group between central autonomic network regions and motor, premotor, frontal, parietal, and visual brain regions. Across both groups, these FC changes were inversely associated with trait anxiety (State-Trait Anxiety Inventory-Trait), trait depression (9-item Patient Health Questionnaire), and negative body image perception (Body Shape Questionnaire) measures, but not with changes in resting heart rate. These results were not accounted for by baseline group FC differences.

CONCLUSIONS

Weight-restored females with AN show a widespread state-dependent disruption of signaling between central autonomic, frontoparietal, and sensorimotor brain networks that facilitate interoceptive representation and visceromotor regulation. Additionally, trait associations between central autonomic network regions and these other brain networks suggest that dysfunctional processing of interoceptive signaling may contribute to affective and body image disturbance in AN.

Neural activation of regions involved in food reward and cognitive control in young females with anorexia nervosa and atypical anorexia nervosa versus healthy controls

Anorexia nervosa (AN) and atypical AN (AtypAN) are complex neurobiological illnesses that typically onset in adolescence with an often treatment-refractory and chronic illness trajectory. Aberrant eating behaviors in this population have been linked to abnormalities in food reward and cognitive control, but prior studies have not examined respective contributions of clinical characteristics and metabolic state. Research is needed to identify specific disruptions and inform novel intervention targets to improve outcomes. Fifty-nine females with AN (n = 34) or AtypAN (n = 25), ages 10-22 years, all ≤90% expected body weight, and 34 age-matched healthy controls (HC) completed a well-established neuroimaging food cue paradigm fasting and after a standardized meal, and we used ANCOVA models to investigate main and interaction effects of Group and Appetitive State on blood oxygenation level-dependent (BOLD) activation for the contrast of exposure to high-calorie food images minus objects. We found main effects of Group with greater BOLD activation in the dorsal anterior cingulate cortex (dACC), dorsolateral prefrontal cortex (DLPFC), hippocampus, caudate, and putamen for AN/AtypAN versus HC groups, and in the three-group model including AN, AtypAN, and HC (sub-)groups, where differences were primarily driven by greater activation in the AtypAN subgroup versus HC group. We found a main effect of Appetitive State with increased premeal BOLD activation in the hypothalamus, amygdala, nucleus accumbens, and caudate for models that included AN/AtypAN and HC groups, and in BOLD activation in the nucleus accumbens for the model that included AN, AtypAN, and HC (sub-)groups. There were no interaction effects of Group with Appetitive State for any of the models. Our findings demonstrate robust feeding-state independent group effects reflecting greater neural activation of specific regions typically associated with reward and cognitive control processing across AN and AtypAN relative to healthy individuals in this food cue paradigm. Differential activation of specific brain regions in response to the passive viewing of high-calorie food images may underlie restrictive eating behavior in this clinical population.

Trait anxiety is associated with amygdala expectation and caloric taste receipt response across eating disorders

Anxious traits are elevated in eating disorders (EDs), are considered risk factors for ED development, and trait anxiety has been linked to ED psychopathology. How trait anxiety relates to ED neurobiology is not well understood. In this study 197 individuals across the ED spectrum (anorexia nervosa n = 91; other specified EDs n = 34; bulimia nervosa n = 56; binge ED n = 16), and 120 healthy controls were assessed for anxious traits and learned to expect and receive caloric or neutral taste stimuli during brain imaging. Amygdala sucrose expectation response differed across groups (Wilk's lambda = 0.945, p = 0.023), and was higher on the left in anorexia nervosa compared to healthy controls (p = 0.002). Expected sucrose receipt response across taste reward regions was not different between groups. In the ED sample, trait anxiety negatively moderated the relationship between amygdala expectation and right dorsal (p = 0.0062) and ventral (p = 0.0046) anterior insula receipt response. A subgroup analysis showed similar results for anorexia nervosa, and partially in bulimia nervosa. Across EDs, appetitive motivation correlated positively with bilateral orbitofrontal cortex, caudate head, and ventral striatal sucrose receipt response (r = 0.215 to 0.179, p = 0.002 to 0.012). Across the study sample, trait anxiety showed an inverted-U-shaped relationship with right (r = 0.147, p = 0.034) and left (r = 0.162, p = 0.016) amygdala expectation response. Amygdala sucrose expectation response is elevated in anorexia nervosa, correlates with sucrose receipt response, and this relationship is negatively moderated by trait anxiety across EDs. Trait anxiety may have an important role in how expectation drives taste stimulus receipt brain response and perhaps food approach in individuals with EDs.

Brain and gut microbiota disorders in the psychopathology of anorexia nervosa

Studies of pathophysiological mechanisms involved in eating disorders (EDs) have intensified over the past several years, revealing their unprecedented and unanticipated complexity. Results from many articles highlight critical aspects in each member of ED family. Notably, anorexia nervosa (AN) is a disorder due to undefined etiology, frequently associated with symptoms of depression, anxiety, obsessive-compulsiveness, accompanied by endocrine alterations, altered immune response, increased inflammation, and dysbiosis of the gut microbiota. Hence, an advanced knowledge of how and why a multisystem involvement exists is of paramount importance to understand the pathogenetic mechanisms of AN. In this review, we describe the change in the brain structure/function focusing on hypothalamic endocrine disorders and the disequilibrium of gut microbiota in AN that might be responsible for the psychopathological complication.

The neurobiological reward system and binge eating: A critical systematic review of neuroimaging studies

OBJECTIVE

Changes in reward processing are hypothesized to play a role in the onset and maintenance of binge eating (BE). However, despite an increasing number of studies investigating the neurobiological reward system in individuals who binge eat, no comprehensive systematic review exists on this topic. Therefore, this review has the following objectives: (1) identify structural and functional changes in the brain reward system, either during rest or while performing a task; and (2) formulate directions for future research.

METHODS

A search was conducted of articles published until March 31, 2022. Neuroimaging studies were eligible if they wanted to study the reward system and included a group of individuals who binge eat together with a comparator group. Their results were summarized in a narrative synthesis.

RESULTS

A total of 58 articles were included. At rest, individuals who binge eat displayed a lower striatal dopamine release, a change in the volume of the striatum, frontal cortex, and insula, as well as a lower frontostriatal connectivity. While performing a task, there was a higher activity of the brain reward system when anticipating or receiving food, more model-free reinforcement learning, and more habitual behavior. Most studies only included one patient group, used general reward-related measures, and did not evaluate the impact of comorbidities, illness duration, race, or sex.

DISCUSSION

Confirming previous hypotheses, this review finds structural and functional changes in the neurobiological reward system in BE. Future studies should compare disorders, use measures that are specific to BE, and investigate the impact of confounding factors.

PUBLIC SIGNIFICANCE STATEMENT

This systematic review finds that individuals who binge eat display structural and functional changes in the brain reward system. These changes could be related to a higher sensitivity to food, relying more on previous experiences when making decisions, and more habitual behavior. Future studies should use a task that is specific to binge eating, look across different patient groups, and investigate the impact of comorbidities, illness duration, race, and sex.

The effects of polyunsaturated fatty acid (PUFA) administration on the microbiome-gut-brain axis in adolescents with anorexia nervosa (the MiGBAN study): study protocol for a longitudinal, double-blind, randomized, placebo-controlled trial

Background

Anorexia nervosa (AN) is a severe psychiatric disease that often takes a chronic course due to insufficient treatment options. Emerging evidence on the gut-brain axis offers the opportunity to find innovative treatments for patients with psychiatric disorders. The gut microbiome of patients with AN shows profound alterations that do not completely disappear after weight rehabilitation. In previous studies, the administration of polyunsaturated fatty acids (PUFA) resulted in effects that might be beneficial in the treatment of AN, affecting the microbiome, body weight and executive functions. Therefore, the MiGBAN study aims to examine the effects of a nutritional supplementation with PUFA on the gut microbiome and body mass index (BMI) in patients with AN.

Methods

This is a longitudinal, double-blind, randomized, placebo-controlled trial. Within 2 years, 60 adolescent patients aged 12 to 19 years with AN will receive either PUFA or placebo for 6 months additional to treatment as usual. After 1 year, the long-term effect of PUFA on the gut microbiome and consecutively on BMI will be determined. Secondary outcomes include improvement of gastrointestinal symptoms, eating disorder psychopathology, and comorbidities. Additionally, the interaction of the gut microbiome with the brain (microbiome-gut-brain axis) will be studied by conducting MRI measurements to assess functional and morphological changes and neuropsychological assessments to describe cognitive functioning. Anti-inflammatory effects of PUFA in AN will be examined via serum inflammation and gut permeability markers. Our hypothesis is that PUFA administration will have positive effects on the gut microbiota and thus the treatment of AN by leading to a faster weight gain and a reduction of gastrointestinal problems and eating disorder psychopathology.

Discussion

Due to previously heterogeneous results, a systematic and longitudinal investigation of the microbiome-gut-brain axis in AN is essential. The current trial aims to further analyse this promising research field to identify new, effective therapeutic tools that could help improve the treatment and quality of life of patients. If this trial is successful and PUFA supplementation contributes to beneficial microbiome changes and a better treatment outcome, their administration would be a readily applicable additional component of multimodal AN treatment.

Trial registration

German Clinical Trials Register DRKS00017130. Registered on 12 November 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06413-7.

Efficacy and safety of antipsychotics and antidepressants in the treatment of anorexia nervosa: a systematic review

INTRODUCTION

The recommendations of the current guidelines are based on low quality evidence. Periodic updating is required, taking recent evidence into consideration.

OBJECTIVE

To synthesise the best available clinical evidence on the efficacy and safety of second-generation antidepressants and antipsychotics in patients with anorexia nervosa.

METHODS

Systematic review (CRD42020150577). We searched PubMed, SCOPUS, Ovid(Cochrane), EMBASE and LILACS for randomised clinical trials performed in patients with anorexia nervosa that evaluated the use of second-generation antipsychotics or oral antidepressants, at any dose and for any length of time, in outpatient and/or hospital treatment, taking weight (body mass index), psychopathological entities and safety as results.

RESULTS

Five studies were included, with four assessed as having a high risk of bias. The evidence indicates that patients receiving treatment with olanzapine or fluoxetine tend to stay in treatment programmes for longer. Olanzapine showed favourable results (one study) in terms of weight gain, but did not show the same results in psychopathology, where the evidence is contradictory.

CONCLUSIONS

In accordance with previous reviews, our work allows us to conclude that there is contradictory information on the efficacy of psychotropic drugs in the treatment of anorexia nervosa. Future work should focus on developing clinical trials of high methodological quality.

Associations between psychosis symptoms and eating disorders among a national sample of U.S. college students

This study aimed to determine the associations between psychosis symptoms and eating disorders among a national sample of college and university students ages 18 to 26 years. Data from the 2020-2021 Healthy Minds Study (United States) were analyzed (N = 96,791). Multiple modified Poisson regression analyses were conducted to estimate the association between four self-reported lifetime psychosis symptoms and a positive eating disorder screen (measured using the SCOFF) and any self-reported lifetime eating disorder diagnosis, while adjusting for demographic and confounding variables. Participants who reported all four lifetime psychosis symptoms were more likely to screen positive for an eating disorder, while participants who reported three lifetime psychosis symptoms were more likely to report any lifetime eating disorder diagnosis. Those who reported a higher cumulative number of lifetime psychosis symptoms and reported any psychosis symptoms in the past 12 months were more likely to screen positive for an eating disorder and report any lifetime eating disorder diagnosis. Psychosis symptoms were associated with eating disorders among a national sample of college students. Health care professionals should be aware of the relationship between psychosis symptoms and eating disorders to ensure effective screening and early-intervention.

Anhedonia in eating disorders: A meta-analysis and systematic review

OBJECTIVE

Anhedonia, or loss of pleasure, is related to deficits in reward processing across a variety of psychiatric disorders. In light of research suggesting abnormal reward processing in eating disorders (EDs), the study of anhedonia in EDs may yield important insights into the role of reward in eating pathology. This meta-analysis and review aimed to provide both a quantitative and qualitative synthesis of the existing literature on this topic.

METHOD

We conducted this research (or these meta-analyses) according to PRISMA guidelines. We searched four databases for both peer-reviewed and unpublished literature, and included studies only if a self-report or clinical interview measure of anhedonia was administered to a sample with an ED diagnosis.

RESULTS

We included 21 studies in the systematic review, and 10 studies in two meta-analyses that compared anhedonia between ED and control samples (n = 9 studies) and within different ED diagnoses (n = 5 studies). Meta-analyses revealed that anhedonia was significantly higher in ED groups compared to healthy controls, but there was no significant difference in anhedonia between ED diagnostic groups. A qualitative review of the literature also suggested that anhedonia may be correlated with increased ED symptom severity.

DISCUSSION

Findings indicated that anhedonia is elevated in EDs and may be a relevant treatment target. Future research should examine how self-reported anhedonia may correlate with components of reward processing in EDs in order to improve theoretical models as well as targeted interventions.

Gastrointestinal Interoception in Eating Disorders: Charting a New Path

PURPOSE OF REVIEW

Abnormal interoception has been consistently observed across eating disorders despite limited inclusion in diagnostic conceptualization. Using the alimentary tract as well as recent developments in interoceptive neuroscience and predictive processing as a guide, the current review summarizes evidence of gastrointestinal interoceptive dysfunction in eating disorders.

RECENT FINDINGS

Eating is a complex process that begins well before and ends well after food consumption. Abnormal prediction and prediction-error signals may occur at any stage, resulting in aberrant gastrointestinal interoception and dysregulated gut sensations in eating disorders. Several interoceptive technologies have recently become available that can be paired with computational modeling and clinical interventions to yield new insights into eating disorder pathophysiology. Illuminating the neurobiology of gastrointestinal interoception in eating disorders requires a new generation of studies combining experimental probes of gut physiology with computational modeling. The application of such techniques within clinical trials frameworks may yield new tools and treatments with transdiagnostic relevance.

Neuromodulation and Eating Disorders

PURPOSE OF REVIEW

We review recent evidence on the use of neuromodulation for treating eating disorders (EDs), including anorexia nervosa, bulimia nervosa and binge eating disorder. We evaluate studies on (a) modern non-invasive methods of brain stimulation, such as transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), (b) electroconvulsive therapy (ECT) and (c) more invasive techniques, including deep brain stimulation (DBS).

RECENT FINDINGS

Most reports on the clinical applications of neuromodulation in EDs are limited to case studies, case series and small clinical trials. The majority have focused on severe, enduring and hard-to-treat cases of AN. In this population, data suggest that both rTMS and DBS have therapeutic potential and are safe and acceptable. High-quality clinical trials in different ED populations are needed which investigate different stimulation methods, sites and parameters, the use of neuromodulation as stand-alone and/or adjunctive treatment, as well as the mechanisms of action.

Increased self-reported delay of gratification in acutely underweight, but not remitted anorexia nervosa

OBJECTIVE

Laboratory experiments using delay discounting tasks have delivered some evidence of an increased capacity to delay reward in anorexia nervosa (AN). Overall, however, findings have been inconclusive and no comprehensive studies of self-reported tendency to forgo immediate gratification in favor of long-term rewards exist in AN.

METHOD

A total of 71 acutely underweight female inpatients with AN (acAN); 52 women long-term weight-recovered from AN (recAN); and 120 healthy control women completed the Delaying Gratification Inventory (DGI). Fifty-two acAN were reassessed after short-term weight rehabilitation. Separate cross-sectional and longitudinal group comparisons tested for differences in DGI subscales (food, physical pleasure, social interaction, money, and achievement) and total scores.

RESULTS

DGI scores were elevated in acAN even after removing food-related items and accounting for comorbid symptoms. DGI scores remained relatively elevated following short-term weight rehabilitation, but no differences were evident between recAN and HC.

DISCUSSION

This study delivers self-report evidence supporting the notion of an increased propensity to delay gratification in individuals acutely ill with AN which does not appear to change with partial weight restoration alone. A reduction in the tendency to delay reward may thus be an important cognitive correlate of long-term recovery in AN.

Anorexia nervosa, conduct disorder, and the juvenile justice system: a case of applying traditional treatment modalities in a non-traditional setting

Background

Anorexia Nervosa is highly comorbid with depressive, anxiety, and obsessive-compulsive spectrum disorders. However, it has not previously been reported as comorbid with antisocial personality traits, except when substance use disorder is also identified. We present an unusual case of a patient with resistant anorexia nervosa and comorbid conduct disorder. This case was also unique in that the juvenile justice system was involved during treatment.

Case presentation

A 13-year-old female was admitted to our pediatric hospital for the treatment of anorexia nervosa. She had a history of violent behaviors toward family members, often jeopardizing her care. During hospitalization, she physically attacked a physician on her care team shortly before she transitioned to an eating disorders treatment program. She was diagnosed with conduct disorder, and following discharge, she attacked her father in a premeditated act. This led to her entry into the juvenile justice system. While under the custody of the juvenile justice system, she was readmitted to our hospital for further treatment of anorexia nervosa. Our treatment strategy included psychotropics, positive reinforcement, close interdisciplinary coordination among the various hospital teams, and the juvenile justice system. Following discharge from her second hospitalization back to the juvenile detention system, our patient maintained a healthy weight and appeared to show improvements in the cognitive distortions related to her eating disorder.

Conclusions

To our knowledge, this is the first reported successful treatment of an individual with resistant anorexia nervosa and conduct disorder. It was likely a combination of weight gain, psychotropic medications, and the structured milieu provided by the juvenile justice system that led to the effective treatment of our patient. This case illustrates that a non-traditional healthcare setting can be an asset to treatment through persistence and close collaboration across institutions.

A Comprehensive Review of Complications and New Findings Associated with Anorexia Nervosa

Anorexia nervosa is a complex and deadly psychiatric disorder. It is characterized by a significant degree of both co-occurring psychiatric diseases and widespread physiological changes which affect nearly every organ system. It is important for clinicians to be aware of the varied consequences of this disorder. Given the high rate of mortality due to AN, there is a need for early recognition so that patients can be referred for appropriate medical and psychiatric care early in the course of the disorder. In this study, we present a comprehensive review of the recent literature describing medical findings commonly encountered in patients with AN. The varied and overlapping complications of AN affect pregnancy, psychological well-being, as well as bone, endocrine, gastrointestinal, cardiovascular, and pulmonary systems.

From Desire to Dread-A Neurocircuitry Based Model for Food Avoidance in Anorexia Nervosa

Anorexia nervosa is a severe psychiatric illness associated with food avoidance. Animal models from Berridge et al. over the past decade showed that environmental ambience, pleasant or fear inducing, can trigger either appetitive (desire) or avoidance (dread) behaviors in animals via frontal cortex, nucleus accumbens dopamine D1 and D2 receptors, and hypothalamus. Those mechanisms could be relevant for understanding anorexia nervosa. However, models that translate animal research to explain the psychopathology of anorexia nervosa are sparse. This article reviews animal and human research to find evidence for whether this model can explain food avoidance behaviors in anorexia nervosa. Research on anorexia nervosa suggests fear conditioning to food, activation of the corticostriatal brain circuitry, sensitization of ventral striatal dopamine response, and alterations in hypothalamic function. The results support the applicability of the animal neurocircuitry derived model and provide directions to further study the pathophysiology that underlies anorexia nervosa.

A Systematic Review of Electrophysiological Findings in Binge-Purge Eating Disorders: A Window Into Brain Dynamics

Binge-purge eating disorders (BP-ED), such as bulimia nervosa and binge eating disorder, may share some neurobiological features. Electroencephalography (EEG) is a non-invasive measurement modality that may aid in research and diagnosis of BP-ED. We conducted a systematic review of the literature on EEG findings in BP-ED, seeking to summarize and analyze the current evidence, as well as identify shortcomings and gaps to inform new perspectives for future studies. Following PRISMA Statement recommendations, the PubMed, Embase, and Web of Science databases were searched using terms related to “electroencephalography” and “binge-purge” eating disorders. Of 555 articles retrieved, 15 met predefined inclusion criteria and were included for full-text analysis. Eleven studies investigated EEG by means of event-related potentials (ERP) in BP-ED individuals: 7 using eating disorder-related stimuli (i.e., food, body image) and 4 using non-eating disorder-related stimuli (i.e., facial expressions or auditory clicks). These studies found significant differences in the N200, P200, P300, and LPP components in BP-ED participants compared to controls, indicating that this population exhibits impairments in selective attention, attentional allocation/processing, and allocation of motivational or emotion-based attention. Five studies investigated EEG using frequency analysis; reporting significant differences in beta activity in fronto-temporal and occipito-temporo-parietal areas in BP-ED individuals compared to controls, revealing a dysfunctional brain network. However, the small number of studies, the heterogeneity of samples, study paradigms, stimulus types, and the lack of an adequate assessment of neuropsychological parameters are some limitations of the current literature. Although some EEG data are promising and consistent with neuroimaging and neuropsychological findings in individuals with BP-ED, future studies need to overcome current methodological shortcomings.

Efficacy and Safety of Antipsychotics and Antidepressants in the Treatment of Anorexia Nervosa: a Systematic Review

INTRODUCTION

The recommendations of the current guidelines are based on low quality evidence. Periodic updating is required, taking recent evidence into consideration.

OBJECTIVE

To synthesise the best available clinical evidence on the efficacy and safety of second-generation antidepressants and antipsychotics in patients with anorexia nervosa.

METHODS

Systematic review (CRD42020150577). We searched PubMed, SCOPUS, Ovid(Cochrane), EMBASE and LILACS for randomised clinical trials performed in patients with anorexia nervosa that evaluated the use of second-generation antipsychotics or oral antidepressants, at any dose and for any length of time, in outpatient and/or hospital treatment, taking weight (body mass index), psychopathological entities and safety as results.

RESULTS

Five studies were included, with four assessed as having a high risk of bias. The evidence indicates that patients receiving treatment with olanzapine or fluoxetine tend to stay in treatment programmes for longer. Olanzapine showed favourable results (one study) in terms of weight gain, but did not show the same results in psychopathology, where the evidence is contradictory.

CONCLUSIONS

In accordance with previous reviews, our work allows us to conclude that there is contradictory information on the efficacy of psychotropic drugs in the treatment of anorexia nervosa. Future work should focus on developing clinical trials of high methodological quality.

Descriptions of Disordered Eating in German Psychiatric Textbooks, 1803-2017

The most common eating disorders (EDs) according to DSM-5 are anorexia nervosa (AN), bulimia nervosa (BN) and binge eating disorder (BED). These disorders have received increasing attention in psychiatry due to rising prevalence and high morbidity and mortality. The diagnostic category "anorexia nervosa," introduced by Ernest-Charles Lasègue and William Gull in 1873, first appears a century later in a German textbook of psychiatry, authored by Gerd Huber in 1974. However, disordered eating behavior has been described and discussed in German psychiatric textbooks throughout the past 200 years. We reviewed content regarding eating disorder diagnoses but also descriptions of disordered eating behavior in general. As material, we carefully selected eighteen German-language textbooks of psychiatry across the period 1803-2017. Previously, in German psychiatry, disordered eating behaviors were seen as symptoms of depressive disorders, bipolar disorder or schizophrenia, or as manifestations of historical diagnoses no longer used by the majority of psychiatrists such as neurasthenia, hypochondria and hysteria. Interestingly, 19th and early 20th century psychiatrists like Kraepelin, Bumke, Hoff, Bleuler, and Jaspers reported symptom clusters such as food refusal and vomiting under these outdated diagnostic categories, whereas nowadays they are listed as core criteria for specific eating disorder subtypes. A wide range of medical conditions such as endocrinopathies, intestinal or brain lesions were also cited as causes of abnormal food intake and body weight. An additional consideration in the delayed adoption of eating disorder diagnoses in German psychiatry is that people with EDs are commonly treated in the specialty discipline of psychosomatic medicine, introduced in Germany after World War II, rather than in psychiatry. Viewed from today's perspective, the classification of disorders associated with disordered eating is continuously evolving. Major depressive disorder, schizophrenia and physical diseases have been enduringly associated with abnormal eating behavior and are listed as important differential diagnoses of EDs in DSM-5. Moreover, there are overlaps regarding the neurobiological basis and psychological and psychopharmacological therapies applied to all of these disorders.

Reward Learning Through the Lens of RDoC: a Review of Theory, Assessment, and Empirical Findings in the Eating Disorders

PURPOSE OF REVIEW

Reward-related processes may represent important transdiagnostic factors underlying eating pathology. Using the NIMH Research Domain Criteria as a guide, the current article reviews theories, behavioral and self-report assessments, and empirical findings related to reward learning in the eating disorders.

RECENT FINDINGS

Data from behavioral tasks suggest deficits in reinforcement learning, which may become more pronounced with increasing disorder severity and duration. Self-report data strongly implicate positive eating and thinness/restriction expectancies (an element of reward prediction error) in the onset and maintenance of eating pathology. Finally, self-report measures of habit strength demonstrate relationships with eating pathology and illness duration; however, behavioral task data do not support relationships between eating pathology and a propensity towards general habit development. Existing studies are limited, but provide preliminary support for the presence of abnormal reward learning in eating disorders. Continued research is needed to address identified gaps in the literature.

Theoretical and Methodological Considerations for Research on Eating Disorders and Gender

Gender is a relevant factor in the etiology of eating disorders (ED) as evidenced by gender-specific components of disordered eating and by the high risk of ED among transgender individuals, in addition to other factors. However, research on connections between ED and gender identity are limited. Researchers who produce explanatory models, content themselves with faulting the sociocultural ideal of slimness for women, but they fail to grasp the connection between culture, gender and the body and they fall short of integrating this perspective into existing psychological knowledge about ED. Psychological research informed by feminist theory has begun to bridge this gap, but this growing area of research needs to be further developed and should include an understanding of ED in persons with all gender identities. This article expands the discussion of gender and ED, by grounding ED in an understanding of gender itself and by discussing methodological implications of this understanding.

Evaluation of spontaneous regional brain activity in weight-recovered anorexia nervosa

Whereas research using structural magnetic resonance imaging (sMRI) reports sizable grey matter reductions in patients suffering from acute anorexia nervosa (AN) to be largely reversible already after short-term weight gain, many task-based and resting-state functional connectivity (RSFC) studies suggest persistent brain alterations even after long-term weight rehabilitation. First investigations into spontaneous regional brain activity using voxel-wise resting-state measures found widespread abnormalities in acute AN, but no studies have compared intrinsic brain activity properties in weight-recovered individuals with a history of AN (recAN) with healthy controls (HCs). SMRI and RSFC data were analysed from a sample of 130 female volunteers: 65 recAN and 65 pairwise age-matched HC. Cortical grey matter thickness was assessed using FreeSurfer software. Fractional amplitude of low-frequency fluctuations (fALFFs), mean-square successive difference (MSSD), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VHMC), and degree centrality (DC) were calculated. SMRI and RSFC data were analysed from a sample of 130 female volunteers: 65 recAN and 65 pairwise age-matched HCs. Cortical grey matter thickness was assessed using FreeSurfer software. Fractional amplitude of low-frequency fluctuations (fALFF), mean-square successive difference (MSSD), regional homogeneity (ReHo), voxel-mirrored homotopic connectivity (VHMC), and degree centrality (DC) were calculated. Abnormal regional homogeneity found in acute AN seems to normalize in recAN, supporting assumptions of a state rather than a trait marker. Aberrant fALFF values in the cerebellum and the infertior temporal gyrus could possibly hint towards trait factors or a scar (the latter, e.g., from prolonged periods of undernutrition), warranting further longitudinal research.

Pharmacological treatment of eating disorders, comorbid mental health problems, malnutrition and physical health consequences

The pharmacological treatment of patients with an eating disorder (ED) often includes medications to treat their ED, comorbid mental health problems, malnutrition and the physical health problems resulting from it. The currently approved pharmacological treatment options for EDs are limited to fluoxetine for bulimia nervosa (BN) and - in some countries - lisdexamfetamine for binge eating disorder (BED). Thus, there are no approved pharmacological options for anorexia nervosa (AN), even though study results for olanzapine and dronabinol are promising. Topiramate might be an additional future option for the treatment of BN and BED. Selective serotonin reuptake inhibitors (SSRI), mirtazapine and bupropion could be considered for the treatment of comorbid unipolar depression. However, AN and BN are contraindications for bupropion. For ED patients with a manic episode, we recommend olanzapine in AN and risperidone in BN and BED; whereas for bipolar depression, olanzapine (plus fluoxetine) seems appropriate in AN and lamotrigine in BN and BED. Acute anxiety or suicidality may warrant benzodiazepine treatment with lorazepam. Proton-pump inhibitors, gastroprokinetic drugs, laxatives and hormones can alleviate certain physical health problems caused by EDs. Therapeutic drug monitoring, pharmacogenomic testing, a more restrictive use of "pro re nata" (PRN) medication, an interdisciplinary treatment approach, shared decision making (SDM) and the formulation of common treatment goals by the patients, their family or carers and clinicians could improve treatment success and safety. Novel genetic, immunological, microbiome and brain imaging research as well as new pharmacological developments like the use of psychedelics, stimulants, novel monoaminergic drugs, hormone analogues and drugs which enhance the effects of psychotherapy may extend our therapeutic options in the near future.

The effect of underweight on female and male reproduction

Chronic energy deficiency can impair the hypothalamic-pituitary-gonadal (HPG) axis and lead to hypothalamic anovulation in underweight women. This review presents the syndromes related to underweight status that are associated with infertility, summarizes the underlying mechanisms, and reviews the available treatment options. Eating disorders, such as anorexia nervosa (AN), constitute the most common cause of infertility in underweight women, who, in addition, experience miscarriages, and sexual dysfunction. The relative energy deficiency in sports (RED-S; former terminology: athlete's triad) involves menstrual dysfunction due to low energy availability, which results in anovulation. Moreover, lipodystrophies, malnutrition, starvation, systematic illnesses (malignancies, endocrinopathies, infectious diseases, advanced chronic diseases, neurologic illnesses), and the utilization of drugs can cause excessive weight loss. They may result in fertility problems due to the loss of adipose tissue and the subsequent hormonal disturbances. Each of these conditions requires multidisciplinary management. Nutritional counseling should target the restoration of energy balance by increasing intake and reducing output. Medical treatment, recommended only for patients who did not respond to standard treatment, may include antipsychotics, antidepressants, or leptin administration. Finally, psychiatric treatment is considered an integral part of the standard treatment.

Strengthened Default Mode Network Activation During Delay Discounting in Adolescents with Anorexia Nervosa After Partial Weight Restoration: A Longitudinal fMRI Study

The capacity of patients with anorexia nervosa (AN) to resist food-based rewards is often assumed to reflect excessive self-control. Previous cross-sectional functional magnetic resonance imaging (fMRI) studies utilizing the delay discounting (DD) paradigm, an index of impulsivity and self-control, suggested altered neural efficiency of decision-making in acutely underweight patients (acAN) and a relative normalization in long-term, weight-recovered individuals with a history of AN (recAN). The current longitudinal study tested for changes in functional magnetic resonance imaging (fMRI) activation during DD associated with intensive weight restoration treatment. A predominately adolescent cohort of 22 female acAN patients (mean age—15.5 years) performed an established DD paradigm during fMRI at the beginning of hospitalization and again after partial weight restoration (≥12% body mass index (BMI) increase). Analyses investigated longitudinal changes in both reward valuation and executive decision-making processes. Additional exploratory analyses included comparisons with data acquired in aged-matched healthy controls (HC) as well as probes of functional connectivity between empirically identified nodes of the “task-positive” frontoparietal control network (FPN) and “task-negative” default-mode network (DMN). While treatment was not associated with changes in behavioral DD parameters or activation, specific to reward processing, deactivation of the DMN during decision-making was significantly less pronounced following partial weight restoration. Strengthened DMN activation during DD might reflect a relative relaxation of cognitive overcontrol or improved self-referential, decision-making. Together, our findings present further evidence that aberrant decision-making in AN might be remediable by treatment and, therefore, might constitute an acute effect rather than a core trait variable of the disorder.

Eating disorders

Eating disorders are disabling, deadly, and costly mental disorders that considerably impair physical health and disrupt psychosocial functioning. Disturbed attitudes towards weight, body shape, and eating play a key role in the origin and maintenance of eating disorders. Eating disorders have been increasing over the past 50 years and changes in the food environment have been implicated. All health-care providers should routinely enquire about eating habits as a component of overall health assessment. Six main feeding and eating disorders are now recognised in diagnostic systems: anorexia nervosa, bulimia nervosa, binge eating disorder, avoidant-restrictive food intake disorder, pica, and rumination disorder. The presentation form of eating disorders might vary for men versus women, for example. As eating disorders are under-researched, there is a great deal of uncertainty as to their pathophysiology, treatment, and management. Future challenges, emerging treatments, and outstanding research questions are addressed.

Cognitive Interpersonal Model for Anorexia Nervosa Revisited: The Perpetuating Factors that Contribute to the Development of the Severe and Enduring Illness

The cognitive interpersonal model was outlined initially in 2006 in a paper describing the valued and visible aspects of anorexia nervosa (Schmidt and Treasure, 2006). In 2013, we summarised many of the cognitive and emotional traits underpinning the model (Treasure and Schmidt, 2013). In this paper, we describe in more detail the perpetuating aspects of the model, which include the inter- and intrapersonal related consequences of isolation, depression, and chronic stress that accumulate in the severe and enduring stage of the illness. Since we developed the model, we have been using it to frame research and development at the Maudsley. We have developed and tested interventions for both patients and close others, refining the model through iterative cycles of model/intervention development in line with the Medical Research Council (MRC) framework for complex interventions. For example, we have defined the consequences of living with the illness on close others (including medical professionals) and characterised the intense emotional reactions and behaviours that follow. For the individual with an eating disorder, these counter-reactions can allow the eating disorder to become entrenched. In addition, the consequent chronic stress from starvation and social pain set in motion processes such as depression, neuroprogression, and neuroadaptation. Thus, anorexia nervosa develops a life of its own that is resistant to treatment. In this paper, we describe the underpinnings of the model and how this can be targeted into treatment.

Emotional Response Inhibition: A Shared Neurocognitive Deficit in Eating Disorder Symptoms and Nonsuicidal Self-Injury

Eating disorder (ED) symptoms often co-occur with non-suicidal self-injury (NSSI). This comorbidity is consistent with evidence that trait negative urgency increases risk for both of these phenomena. We previously found that impaired late-stage negative emotional response inhibition (i.e., negative emotional action termination or NEAT) might represent a neurocognitive mechanism for heightened negative urgency among people with NSSI history. The current study evaluated whether relations between negative urgency and ED symptoms similarly reflect deficits in this neurocognitive process. A total of 105 community adults completed an assessment of ED symptoms, negative urgency, and an emotional response inhibition task. Results indicated that, contrary to predictions, negative urgency and NEAT contributed independent variance to the prediction of ED symptoms, while controlling for demographic covariates and NSSI history. Worse NEAT was also uniquely associated with restrictive eating, after accounting for negative urgency. Our findings suggest that difficulty inhibiting ongoing motor responses triggered by negative emotional reactions (i.e., NEAT) may be a shared neurocognitive characteristic of ED symptoms and NSSI. However, negative urgency and NEAT dysfunction capture separate variance in the prediction of ED-related cognitions and behaviors, distinct from the pattern of results we previously observed in NSSI.

The promise of neurobiological research in anorexia nervosa

PURPOSE OF REVIEW

This article reviews new research in the context of existing literature to identify approaches that will advance understanding of the persistence of anorexia nervosa.

RECENT FINDINGS

Neuroscience research in anorexia nervosa has yielded disparate findings: no definitive neural mechanism underlying illness vulnerability or persistence has been identified and no clear neural target for intervention has emerged. Recent advances using structural and functional neuroimaging research, as well as new techniques for applying and combining these approaches, have led to a refined understanding of changes in neural architecture among individuals who are acutely ill, have undergone renourishment, or are in recovery/remission. In particular, advances have come from the incorporation of computational and translational approaches, as well as efforts to link experimental paradigms with illness-relevant behavior. Recent findings converge to suggest abnormalities in systems involved in reward learning and processing among individuals with anorexia nervosa.

SUMMARY

Anorexia nervosa is associated with neurobiological abnormalities. Aberrant learning and reward processing may contribute to the persistence of illness. To better utilize new techniques to understand the neural mechanisms of persistent anorexia nervosa, it may help to distinguish stages of illness and to link neurobiology with maladaptive behavior.

Functional Connectivity Patterns and the Role of 5-HTTLPR Polymorphism on Network Architecture in Female Patients With Anorexia Nervosa

Introduction

Recent neuroimaging studies suggest that anorexia nervosa (AN) symptoms emerge from failures in the relationships between spatially distributed networks that support different cognitive, emotional, and somatosensory functions. The 5-HTTLPR genotype has been shown to modulate all these abilities in AN, as well as the connectivity patterns between brain regions that support their functioning. This study aims at exploring the presence of any difference in functional connectome properties between AN patients and healthy controls (HC) by means of graph theory tools. The effect of 5-HTTLPR genotype on regional and global network characteristics in AN and HC was also explored.

Methods

A sample of 74 subjects (38 HC, 36 AN) underwent a resting state functional magnetic resonance imaging and was genotyped for 5-HTTLPR polymorphism. Comparisons of network properties were made between the AN and HC groups and, within each group, between 5-HTTLPR carriers of low-functioning alleles and carriers of the long–long genotype.

Results

Patients with AN displayed lower network clustering than HC (p = 0.04 at Mann–Whitney U test). Based on both degree and betweenness, a different distribution of network hubs emerged in the two groups. In particular, the anterior part of the anterior cingulate cortex was a hub only in the patient group. A correlation emerged between differences in brain volumes between patients and HC and differences in degree values of basal ganglia, nodes in the insula, and those in the parietal cortex. Carriers of the short allele of the 5-HTTLPR polymorphism were characterized by lower small-world properties (p = 0.027) and modularity (p = 0.031) in the patient group, and a trend toward higher modularity (p = 0.033) and small-world values (p = 0.123) in the HC group.

Discussion

Patients with AN showed differences in hubs distribution, providing evidence of the presence of a different functional architectural backbone in this group. Since some correlation emerged between different degree values of nodes and differences in volumes, further longitudinal studies are warranted to better understand the role of malnutrition on brain network architecture. The opposite effects of 5-HTTLPR polymorphism on global network characteristics in the two groups suggest an interaction of the short allele and malnutrition in modulating brain network properties.

Recent advances in therapies for eating disorders

Eating disorders are serious psychiatric illnesses with high rates of morbidity and mortality. Effective treatments have traditionally included behaviorally focused therapies as well as several medication strategies. Recent years have seen promising developments in these treatments, including additional support for family-based approaches for children and adolescents, new evidence for "third-wave" behavioral therapies, and new support for the use of lisdexamfetamine for binge eating disorder and olanzapine for anorexia nervosa. Case study and pilot data are beginning to show limited support for neuromodulatory interventions targeting brain regions thought to be involved in eating disorders. This review summarizes treatment developments over the last several years and points towards future directions for the field.

How do we target the factors that maintain anorexia nervosa? A behaviour change taxonomical analysis

All psychological treatments for anorexia nervosa appear to have equal (albeit modest) effects. This may be explained because they target similar processes. Although different psychological treatments have been developed for anorexia nervosa treatment, their taxonomical components have not been compared. This study undertook a taxonomical analysis of behaviour change techniques (BCTs), using the CALO-RE analysis tool, from the manuals of Enhanced Cognitive Behavioural Therapy (CBT-E), Maudsley Model of Anorexia Nervosa Treatment for Adults (MANTRA), Family Based Therapy (FBT), Specialist Supportive Clinical Management (SSCM), and Focal Psychodynamic Psychotherapy (FPT). The highest number of BCTs were found in FPT (72,5%), and the lowest were in SSCM (30%). The other interventions had a similar range of BCTs which mainly focused on goal planning (FBT (50%), CBT-E (47.5%), MANTRA (42.5%)). Modelling, shaping, and training communication, self-monitoring, and fear arousal were the less commonly used BCTs across manuals. Manualized psychological interventions for people with anorexia nervosa share a substantial number of behaviour change techniques which might explain their similar levels of effectiveness. New strategies may be needed in order to improve outcomes.

A Transdiagnostic Perspective on Social Anhedonia

Humans are highly social beings, yet people with social anhedonia experience reduced interest in or reward from social situations. Social anhedonia is a key facet of schizotypal personality, an important symptom of schizophrenia, and increasingly recognized as an important feature in a range of other psychological disorders. However, to date, there has been little examination of the similarities and differences in social anhedonia across diagnostic borders. Here, our goal was to conduct a selective review of social anhedonia in different psychological and life course contexts, including the psychosis continuum, depressive disorder, posttraumatic stress disorder, eating disorders, and autism spectrum disorders, along with developmental and neurobiological factors. Current evidence suggests that the nature and expression of social anhedonia vary across psychological disorders with some groups showing deficient learning about, enjoyment from, and anticipation of the pleasurable aspects of social interactions, while for others, some of these components appear to remain intact. However, study designs and methodologies are diverse, the roles of developmental and neurobiological factors are not routinely considered, and direct comparisons between diagnostic groups are rare-which prevents a more nuanced understanding of the underlying mechanisms involved. Future studies, parsing the wanting, liking, and learning components of social reward, will help to fill gaps in the current knowledge base. Consistent across disorders is diminished pleasure from social situations, subsequent withdrawal, and poorer social functioning in those who express social anhedonia. Nonetheless, feelings of loneliness often remain, which suggests the need for social connection is not entirely absent. Adolescence is a particularly important period of social and neural development and may provide a valuable window on the developmental origins of social anhedonia. Adaptive social functioning is key to recovery from mental health disorders; therefore, understanding the intricacies of social anhedonia will help to inform treatment and prevention strategies for a range of diagnostic categories.